Paul Krugman cites Greg Mankiw:
The Keynesian moment: Greg has this exactly right:
IF you were going to turn to only one economist to understand the problems facing the economy, there is little doubt that the economist would be John Maynard Keynes. Although Keynes died more than a half-century ago, his diagnosis of recessions and depressions remains the foundation of modern macroeconomics. His insights go a long way toward explaining the challenges we now confront.
I think it’s worth saying a bit more about why, exactly, we’re in such a Keynesian moment. If Keynes receded in our consciousness over the past few decades, it wasn’t mainly because of uninformed criticisms from the right; it was because central bankers seemed to have everything under control. Uncle Alan and his counterparts, by controlling the money supply, could do the job of stabilizing the economy, and Keynesian fiscal policy seemed irrelevant. Now, Keynes understood the role of monetary policy quite well, and believed that it had been effective in the past. What he argued, however, was that there were situations in which monetary policy could do no more — and that the world economy he lived in was facing such a situation:
To-day and presumably for the future the schedule of the marginal efficiency of capital is, for a variety of reasons, much lower than it was in the nineteenth century. The acuteness and the peculiarity of our contemporary problem arises, therefore, out of the possibility that the average rate of interest which will allow a reasonable average level of employment is one so unacceptable to wealth-owners that it cannot be readily established merely by manipulating the quantity of money. So long as a tolerable level of employment could be attained on the average of one or two or three decades merely by assuring an adequate supply of money in terms of wage-units, even the nineteenth century could find a way. If this was our only problem now—if a sufficient degree of devaluation is all we need—we, to-day, would certainly find a way.
Archaic language, but he was describing a situation very much like the one we face now. To be sure, Keynes failed to foresee the postwar rise of the “marginal efficiency of capital” — the way that economic growth combined with inflation would create an environment in which interest rates were high enough in normal times that monetary policy was effective at fighting slumps. Hence the long era in which Keynes didn’t seem all that relevant. But his analysis remained as valid as ever, under the right conditions. Those conditions reappeared first in Japan during the 90s; now they’re everywhere.
And in the long run, it turns out, Keynes is anything but dead.